This invention relates to certain thermoplastic elastomer compositions comprising three different types of polymeric materials, such compositions being characterized by very good processability, high tensile strength, good oil and ozone resistance, and low flammability.
It is well known to blend polymeric materials to products having desirable properties. In order to achieve good blending to a homogeneous product, it is necessary to select starting materials that are compatible with one another, that is, can be dispersed in one another without separating into distinct phases. Such homogeneous blends usually can be processed in ordinary equipment as easily as their individual components. However, in rare cases, polymeric materials that can be readily processed by themselves and that are compatible with one another do not form blends that can be processed as readily.
For example, a copolymer of chloroprene with an .alpha.,.beta.-unsaturated carboxylic acid such as methacrylic acid has excellent elasticity, tensile strength, and light and ozone resistance. Copolymers of ethylene with .alpha.,.beta.-unsaturated carboxylic acids can be crosslinked with certain metal ions to tough resins. Each of these can be fabricated in conventional extruding or injection-molding equipment. However, when they are blended with each other, the resulting blend, although homogeneous, is not readily processable and cannot be extruded or injection-molded.
It is, therefore, desirable to provide readily processable blends of copolymers of chloroprene with .alpha.,.beta.-unsaturated carboxylic acids with copolymers of ethylene with .alpha.,.beta.-unsaturated carboxylic acids.